New cancer gene therapy research from A. Azatian and colleagues discussed.(Report)

According to recent research published in the Journal of Gastrointestinal Surgery, "The thymidine kinase gene of the herpes simplex virus (HSV-tk) is a suicide gene when administrated with the prodrug ganciclovir (GCV). This study investigated the effectiveness of HSV-tk activation as gene therapy for gastroesophageal junction and gastric adenocarcinomas using either the stress-inducible Grp78 promoter or the murine leukemia virus long-terminal repeat (LTR) promoter."

"The HSV-tk gene, controlled by either the Grp78 promoter or the LTR promoter, was transduced into the gastroesophageal junction adenocarcinoma cell line SK-GT-5 and the gastric adenocarcinoma cell line MKN-74. Cell viability after exposure to varying concentrations of GCV was compared. The same cell lines were used to develop a nude mouse model for studies of the HSV-tk/GCV effect in vivo. The effect of intraperitoneal GCV injection on growth of the subcutaneous tumors was measured. HSV-TK expression was measured by Western blot and reverse transcription polymerase chain reaction. Cell viability in vitro was significantly lower in the HSV-tk expressing (HSV-tk+) cells compared to control (no HSV-tk) cells after exposure to GCV. MKN-74tk+ cells were more sensitive to GCV killing than SK-GT-5tk+ cells. After culture with 1 mu g/ml GCV for 10 days, MKN-74/tk cells were totally killed, whereas most SK-GT-5/tk cells survived. Cell viability was significantly lower under glucose starvation conditions when HSV-tk expression was regulated by the Grp78 promoter compared with the LTR promoter. MKN-74 tumors formed with HSV-tk+ cells in nude mice were eliminated after administration of GCV for 3 weeks, but GCV had no effect on tumors formed from HSV-tk- cells. Eradication of tumor formed with Grp78-tk cells was faster than that with LTR-tk cells. HSV-TK protein and mRNA were expressed in the transduced, but not the non-transduced tumors. HSV-tk xwith ganciclovir ...